Process for radio direction, locating observation, and the like



y 25, 1933- F. L. E. JACQUEMIN 1,919,556

PROCESS FOR RADIO DIRECTION, LOGATING OBSERVATION, AND THE LIKE Original Filed April 22. 1927 2 Sheets-Sheet 1 Fig.1

July 25, 1933. F. E. JACQUEMIN PROCESS FOR RADIO DIRECTION, LOCATING OBSERVATION, AND THE LIKE Original Filed April 22, 1 27 2 Sheets-Sheet 2 INVENTO RL FLE J BY '7'- M ATTY RNEY Patented July 25, 1933 UNITED- STATES PATENT OFFICE FRANCOIS LOUIS EDOUARD JACQUEMIN, OF PARIS, FRANCE, ASSIGNOR '10 socm'rr:

2 I ANONYME DES ONDES DIRIGEES PROCESS FOR RAIiIO DIREOTION LOCATING OBSERVATION, AND THE LIKE Applicatiouflled April 22,1927, S erial;1o. -185,8 88,' and a rmnana ar; 122s. Renewed a... 1, 1982.

This invention relatesto means'for generating by the .aid offtwo or more radio transmitters an interference observation field between radio waves which are of the 6 same wave length but are out of phase.

A11 object of the invention is to guide an aeroplane or other moving object equipped with a radio receiver along a fixed path through observationof the interference of radio waves transmitted from two distant antennae. One antenna transmits an unmodulated wave having a constant length, the other antenna transmits a modulated wave having the same constant wave length. The radio observer in the aeroplanethrough observation of the interfering waves reaching him is enabled t9 maintain his position along thefixed path.

In order that the invention may more readily be understood, the principle thereof will now be explained with reference to the drawing. Figure 1 of the drawing shows the two transmitters which set up an interferin field. Figure 2 shows the lines of inter erence of the field from the transmitters shown by Figure 1. Figures 3, 4 and 5 are vector dia rams showing the field relation of the radio waves emitted by the two stations and received at a given point in the field. Figure 6 shows the field covered by the sweeping of a nodal axis. Figure 7 shows the signals received at stations near and within the zone swept by the nodal axis.

Let it be supposed that there is a radiating system A provided with an emitting station E for sustained waves which emits radio waves (primary waves) and that in the field of the antenna there is a second aerial B emitting radio waves of the same frequency (secondary waves) out of phase to a constant degree with respect to the primary waves.

The second aerial need not be provided with its own source of energy and the secondary waves may only be primary waves reflected by the aerial B; or again, the aerial B may be fed from the emission of station E either with or without the insertion of an emplifier or phase changing device.

If the secondary emission be modulated or varyin In a radio receiver at C by y system M, (for example, by breakmg the circuit of the aerial B periodically, its wave length, or by varying its resistance the following phenomena, due to .the interference between the modulated and non-modulated fields will be observed.

1. The intensity of reception of the modulated emission at any omt C (Figure 2) depends on .the phase isplacement prevailing at such point C between the primary waves and secondary waves. This phase displacement is a function of several parameters and especially of the difference 'CA-CB (CA minus GB) of the distances primary and secondary of C from th aerials.

For certain values of such difference, the intensity of reception becomes nil; for others it becomes maximum. When CA-CB varies an amount equal to a quarter of the wave length of the waves emitted, the intensity of reception passes from maximum to zero.

Suppose now for example that the transmitter aerial A (see Figure 1) sends forth an unmodulated carrier wave of a certain fre uency and the transmitter aerial B sends fort a carrier wave having the same frequency but modulated. Referring now to Figures 3, 4 and 5, the fields. produced at C (Figure 2) by the emissions from A and B are represented one by a vector RX of a constant am litude and the other by the vector XY 0 an amplitude periodically variable between the values KY and zero, if the wave emitted at B be totally modulated. The resulting field varies thus periodically between the values RX and RY. (Figure 2) the periodical variation of the field between these two values produces a sound having the frequency of the modulation at B. No sound is heard when the values of the vectors RX and RY are equal. The sound is a maximum when the diflerence between both cases whether the angle s is equal to zero or to 180 the amplitude variation of the resultant field is equal to KY and the sound has maximum intensity. Figure 5 shows the conditions when the vectors RX and RY are equal and no sound is heard at the receiver. The points at which the signals are not heard fall upon lines which are called the nodal lines of the field and the points at which the si nals are heard with maximum intensity all upon lines whichare called the ventral lines of the field. These nodal and ventral lines are represented by Figure 2 as the hyperbolic lines HM and HN. The lines along which interfering waves from two similar emitters, such as the two prongs of a tuning fork, arrive to cause wave interference were first proved to be hyperbolic curves by the Weber Brothers (see page 273 of On Sound by John Tyndall published by Longmans, Green & Company, London 1867). In the Weber experiments identical non-modulated waves created lines of interference in their field. In the invention herein disclosed, the waves from one station are modulated and the waves from the other station are non-modulated. With this arrangement zeros of sound are obtained at a receiver even though the field strength of the secondary station may be considerably less than that of the primary station.

2. The zero strength hyperbola HN and the maximum strength hyperbola HM and their asymptotes ASN and ASM with which they substantially coincide when the distance CA is sufliciently large are thus easily observable and allow certain directions to' be marked The angular separation on of two consecutive zero and maximum asymptotes ASN and ASM'may, moreover, be adjusted to a selected value for example by varying the length of wave omitted.

The marking may, moreover, be improved in many ways, for example:

(a) By employing in place of a single aerial B two or more combined aerials whose modulations may be of the same or different frequencies, and displaced in or out of phase by a definite amount with one another.

(6) By employing an emission of periodically varying wave length which effectively periodically displaces all the nodal and ventral lines from their initial position.

(a) By varying the phase of the waves of the secondary aerial or aerials. This variation of phase may be accomplished, for example, by varying the actual wave length of the secondary aerial or by modifying the transmission line from A to B in the case where the oscillations of B are controlled by those of A over such a line.

Suppose now that the phase of the waves from the secondary aerial B is periodicall varied, while the wavesfrom the aerial X (IA-CB has the same value, t at is on the h perbolaa such as HM and HN (Figure 2;. The locations where the dephasage angle (p has constant values at a definite time is thus madeu of one or more hyperbolae, the number 0 such hyperbolae being the greater as the distance. AB is large with res ect tothe length of the wave emitted.

hese nodal and ventral h perbolae periodically oscillate to both si es of their midposition when the angle a is periodically varied.

In particular in the case of the single secondary, if the phase of the waves from such variable aerial is rendered variable in accordance with a. determined law, the zero and maximum lines of the interference field will oscillate from side to side of theirmidposition according to the same law. At any point of the field, the receiver, therefore will not detect a consistent sound but a sound of variable amplitude passing or not through zero according as this point is or is not in the zone swept by the zero line ASN. Outside this zone there will be a maximum and a zero period. In this zone there will be two maxima and two minima per period and the maxima which will follow two consecutive minima will possess greater difference of amplitude as the point is set further and further from the mid-nodal line. It is only when the point of observation is upon the midosition of this line that the maxima will e of equal amplitude. The equality may therefore serve and suffice to define the girl-action of the zero line of the interference It is desirable that the law of variation of base is such that the passages of the osc ating nodal line become separated by two equal periods of time; for example, .a law such that the angular speed of the displacement of the nodal line remains constant, or one that may be represented by a symmetrical graph such as a sine wave may be selected. The sensation of isochronism obtained in the axis will define this axis with precision.

This phenomena can be more easily understood with reference to Figures 6 and 7. The nodal line FG sweeps the zone in the sector FG FG At a point H near F G exterior the swept zone, the intensity of recelption will lessen without becoming null w en FG approaches FG and will increase when FG moves toward FGz. This is repfit;

n arrives on FG, the course of the curve remains the same, but-theminima are void as shown by curve b of Figure 7. In the interior of the swept zone at point D, the intensity of the reception becomes zero twice at periods of unequaltime. This is shown by curve a of Figure 7. Finally at E at the' mid-point of the nodal axis FG the intensity becomes zero twice a period at equal intervals of time, as shown by curve (A of Figure 7. The intensity of the signals received is almost constant when the receiver is far from the swept zone and undergoes a periodical weakemng more and more clearl indicated as it approaches the zone. en the zone is entered, there is a halving of the minimum periods, the two minima being very near at first and becomin equidistant when the receiver arrives on t e mid-position of the nodal axis.

(d) By the variation of the characteristics of the secondary .waves and in articular the modulation note so as to al ow the. two zones situated along the mid-nodal line to be differentiated.

As an example, if the modulation note of the secondary antenna be so varied that with phase displacement in front of the midphase, there corresponds'a note N and with phase displacement lag there corresponds a note N the consecutive maxima will alternately be of the note N then of the note On one side of the mid minimum line the note N will be predominant, on the other side the note N will be predominant, the listener, therefore, will be able to tell on which side of the line he is. All the combinations based upon these rinciples of the variation of one or more aracteristics of the secondary emission in connection with the variation of coming within t vention.

Of course, what has been set out for an acoustic note may be repeatedfor optical, mechanical, or telemechanical phenomena.

The number of lines of zero intensity depend on the relation of the wave length of the emitting waves to the distance between the two antennae. The larger this relation is, the fewer nodal lines there are and the more widely separated they are. The wave length is chosen to be such that the axes are few and easily identified, and this condition is reached when the length AB is near the length of the wave utilized. The two emitting stations are disposed on each side of the fixed path in such a way that the nodal axis coincides with the fixed path along which it is intended that the airplane shall fly. The chosen nodal axis is made to oscillate periodically to either side of its mid-position, and, in so oscillating, it sweeps over a comparatively narrow zone. The airplane 1phase will be considered as e scope of the present incrossing this zone will notice the intensity of the signal becoming zero at first, once at intervals of time equal to the period of sweep- -inflg, then twice a period at unequal interv s, and, finally, when it is at the mid-position of the nodal axis, the signal will become maximum and zero at equal intervals of time. A modification of the modulation fretfiiency to give the distinctive notes N and 2 described above concomitant with the phase variation enables it to be known at the airplane on which side of the mid-nodal line the airplane is traveling. It is thus possible to guide the airplane over the fixed path by observation of the signals heard.

If reception takes place at A or very near to A with respect to the distance AB, the intensity of reception will vary with the' distance AB. It will pass through the maxima and minima every time the distance AB varies a one-quarter of the wave length of the wave emitted at A. By counting the number of maxima and minima in a predetermined time, the speed of movementbf B with respect to A (approaching or receding), will be known.

If the emission at A is directive bearings can be ascertained at the same time.

This measure is also possible even if the aerial B is not modulated. In this case it will be sufiicient to arrange for example, in the neighborhood of the primary emission a modulated aerial tuned to the wave length of emission and so arranged that unless there be another aerial in the field,

its modulation is not perceptible. This allows one to note at A any body which can act'as a secondary antenna without it being necessary for such body to participate in the observation and, therefore, without the necessity for an observer thereat knowing that such observation is being made (ships, aeroplanes, etc.).

In place of usin an auxiliary modulated antenna it is possi 1e to perceive waves reflected by a non-modulated aerial either by heterodyning at reception or by employing as emitter a group of two aerials (loops, for example) the resultant strength of reception at the receiver being rendered perceptible by modulation of the output of one of the aerials, the arrangement being such that this resultant strength of reception is zero unless a non-modulated aerial be present. The distance AB ma further be measured by observing the di erence or variation in wave length required to give two successive maxima of reception when the length of emission is varied.

Finally an appreciation of the distance AB may be obtained from a knowledge of the displacement of the nodal and ventral lines as above explained. With these indication and for a given station it is possible to draw up in advance a true hertzian chart which allows to be noted the sition in direction, distance, speed an direction -.of movement of objects adapted toact as secondary vibrators. All this requires the operation onl of the primary emitter under control. he secondary vibrator has no active role and an observer there is unaware of the observation to which he is subjected. This is a process of 'locatin upon the ground fixed or. movm objects, 0 geodetic points, nautical or aeri navi ting bodies etc.

- en referring to the changing or varyof the phase relation in the claims, it is t d be understood that any method (such as periodically breaking one of the circuits or varying its wave length or its resistance.)

which will have the result of changing the interference pattern, is'to be included within such phase.

I claim: 0

1. Themethod of determlning the position of an object which comprises emitting sustained radio waves of the same wave length from two spaced points, and modulating radio waves emitted from only one of said points to form a special interference pattern havin at least one nodal axis.

2. The met 0d of determining the posi-' tion of an ob'ect which comprises emitting sustained ra i0 waves of the same wave len h from two spaced points, modulatm r 10 waves emitted from only one of sai Y points to form a special interference pattern having at least one nodal axis, and changing the phase relation of said waves between predetermined limits to sweep said axis across a predetermined field.

3. The method of determining the position of an object which comprises emitting sustained radio waves of the same wave length from two spaced points, modulat' radio waves emitted from only one 0 said points to form a special interference pattern having at least one nodal axis, changing the phase relation of said waves between predetermined limits to sweep said axis across a predetermined field, and modifgingrby a certain amount for a definite time t e equency of modulation of the modulated radio waves emitted from said one point to differentiate the two sides of the eld from one another.

4. The method of determining the posias tion of an object which comprises emitting radio waves of the same wave length from two spaced points to form an interference pattern having a nodal axis, changing the phase relation of the said waves between predetermined limits to sweep said axis across a predetermined field, and impressing adistinctive modulated note on the waves emitted from one of said points to indicate the position of said object relative to a preas determined position of said 5. The method "of determining the posi-'. tion of an object which comprises emitting radio waves of the same wave length from two spaced ints to form an interference pattern having a nodal axis, changing the phase relation of said waves between preetermined limits to sweep said axis across said field, and im ressing distinctive contrast' modula notes on the waves emitte from one of said points-to indicate the position of said ob'ect relative to a predetermined position 0 said axis.

6. The method of determining the position of an object which comprises emitting from two spaced points radio-waves of the same wave length to form an interference pattern having a nodal axis, the mid-position of which corresponds to the mean difference of phase of the emitted waves,

changing the phase relation of said waves to sweep said axis across said ob'ect, and impressing a distinctive modulate note on the waves emitted from one of said points to indicate the position of said object rela tive to the mid-position of said axis.

7. The method of determining the position of an object which comprises emitting from two spaced points radio waves of the same wave length to form an interference pattern having a nodal axis, the mid-position of which corresponds to the mean difference of phase of the emitted waves, changing the phase relation of said waves to swee said axis across said object, and impressing distinctive contrasting modulated notes on the waves emitted from one of said points to indicate the position of said object relative to the mid-position of said axis, the waves emitted from the other point being unmodulated.

8. The method f guiding a moving object along a fixed path which comprises emitting on each si e of said path radio waves of the same wave length and form ing an interference pattern having a nodal axis along said pat the mid-position of which axis corresponds to the mean difference of phase of the emitted waves, changing the phase relation of saidwaves to sweep said axis across said path and said object,

and impressing a distinctive modulated note on the waves emitted from one side of said path to indicate the positionof said object relative to the position of said axis.

9. The method of guiding a moving object along a fixed path which comprises emitting on each side of said path radio waves of the same wave length to form an interference pattern having a nodal axis along said path, the mid-position of which axis corresponds to the mean difference of phase of the emitted waves, changing the phase relation of said waves to sweep said axis across said path and said object, and impressmg distinctive contrasting modulated notes on the waves emitted from only one side of said path to indicate the position of said object relative to the mid-position of said axis, the waves emitted from the other side of the path being unmodulated.

10. The method of determining the posi-' tion of an object which comprises emitting from two spaced points radio waves of the same wave length to form an interference pattern having a nodal axis the mid-position of which axis corresponds to the mean 

